The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Powertrain architectures comprise torque-generative devices, including internal combustion engines and electric machines, which transmit torque through a transmission device to a vehicle driveline. Such powertrain systems include parallel-hybrid systems and compound-split hybrid systems, wherein tractive torque to one or more wheels is generated by the internal combustion engine, the electric machine, or a combination thereof through a transmission device. Such systems typically include an electric power system operative to generate and transmit torque through the transmission, and comprise the electric machine and an electrical energy storage device (ESD) operatively connected via power electronics devices. The electric machine comprises a motor/generator operable to generate tractive torque for input to the transmission, independently of torque input from the internal combustion engine. The electric machine is operable to transform vehicle kinetic energy, transmitted through the vehicle driveline, to electrical energy potential that is storable in the ESD. A control system monitors various inputs from the vehicle and the operator and provides operational control of the powertrain system, including controlling transmission gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange between the ESD and the electric machine.
A primary motivation for using a hybrid powertrain system is to improve vehicle fuel economy by utilizing the electric machine to generate some or all of the tractive torque in response to specific operator torque requests, e.g., acceleration events, thus reducing fuel consumption. Furthermore, vehicle kinetic energy can be used to generate electrical energy during vehicle operation such as braking events, thus recharging an electric storage device, commonly a battery.
One operating parameter for a hybrid powertrain system is state of charge (SOC) of the ESD, which is a known parameter that is readily determinable. It is preferable to maintain the SOC of the ESD within a range of values, to optimize service life of the ESD, and prevent damage due to overcharging and excessive discharging.
Vehicle operators often follow a predictable set route to achieve a destination. Examples of this include driving between a place of residence to and from a place of work. Other routes include, e.g., to school, or to a shopping facility. Each set route can be characterized in terms of total distance traveled, operator braking events occurring at specific distances, and operator torque requests.
It would be advantageous to use characteristics of a specific set driving route to manage operation of a hybrid powertrain system to optimize fuel economy and reduce fuel consumption. Such a system is described hereinafter.